I visited JWT on tuesday to have my computer tuned. On their new dyno which hooks up to the hubs the car hit 398 FWHP and fell off at 5500 rpm because the fuel pressure dropped off. Jim said I probaably would have hit 450 with the proper pressure. Has anyone else encountered this problem? We tried a nismo fuel pressure regulator but the fuel press. still didn't hold. What's going on? I am using 370 injects and a walbro 255 hi fo fuel pump.

 

i dunno but...

 

could be a weak pump....


hey ron

 

you have the JWT cams and valve springs , right?
could you list your mods? :>
Thanks!

EDIT: OK did some quick research..........your sig
"96 I30, Built engine, built tranny, 12lbs of SCed boost, 75 shot N2O, aftercooler, and H2O injection
no rice but plenty of meat!!"
3.5 VQ oil pump
could you compile a complete list of exact mods please!? :>

EDIT2: I think you need bigger injectors

 

Nice figures...Must be nice to have that much ooomph. Hope that the fuel pump would fix the problem and you can get even better.

 

is the nismo fuel pressure regulator adjustable??

 

Yowzah! What maf are you using? Are you using constant 3 bar fuel pressure or do you use an fmu?

I agree, it sounds like you need to go to 550's.

 

Weak pump, maybe.

What was your fuel pressure at 5500rpm

Acording to my math your injectors are maxed out, time for 555cc.

 

Nice numbers, I think you need bigger injectors.

I30krab, I am currently rebuilding my 98's VQ30DE. I am trying to decide on what oil pump to go with. I saw that you are using a VQ35's pump. My choices are a toga high volume pump or the VQ35's. What would you suggest I go with? The toga costs $129 and I don't know about the VQ35's price. I know this is off the threads topic but I appreciate your help.

 

Did you by chance ask whether or not they were considering producing an ECU for the 98-99 Maximas? Or did you get a business card? None of us has been able to get in contact with JWT for a LONG time regarding this issue- and anything would help about now....

 

They probably won't make a 98-99 as they've been promising for the last 5 years. The only option for an ecu upgrade is to re-pin the 99 spec connector to the 95-96 spec and live with a CEL. Otherwise you'll have to buy a stand alone engine management.

 

I definitely would go with the VQ35 oil pump. It drops in like it was made for our motors and I get twice the oil pressure compared to the VQ30. You know it works, why try another unproven pump?

Call Joe at Infinity of Scottsdale for the latest price!

 

I never discussed this issue with Jim or Clark.

I do know that Ben always answers the phone and he knows whats going on in their shop.

 

Hi Brett,
we're working on the prblem now and I'll keep you posted.

 

I have so many mods that it's hard to remember them!

Jim and Clark think the walbro 255 pump and the 370 injectors along with the nismo fuel pressure regulator should easily work, we just have to make sure everything is working properly and especially check out for voltage drop at the fuel pump. This is a common problem.

 

Yes it has to be adjustable for custom applications!

 

I am using the 96 3300TT maf and it still has plenty of voltage.
I don't use an FMU because the pressure is managed by the ecu. As of now I aguess it is 3 bars.

 

Right now we're checking these parameters. If we can't fix the problem without going to 550 injs, forget it! Buying and installing these are too expensive and time consuming, and I will have to suffer with 400 horses at the front wheels!! It could be worse.

 

You could have JWT reprogram the ecu for higher fuel pressure, I think. Just a thought.

 

Thanks for the reply, I'll try it.

 

If you could compile a list, that would be awesome!
You have the cams and valve springs, right?